Another option is to call Bill at Ateco Marine. He has various upgrade packages for the 502 MPI. Mine are now 540's with Dart Pro 1 heads and made 630hp at 5300rpm's using the merc mpi intake and fuel injection system (MEFI 3). They look like stock 502 mpi's, but boat runs about 10mph faster and they idle like stock motors as well. Third year and 80+ hours on the motors and very happy.

whats the cam specs and pistons that are in these, can you post the dyno sheet...........4.500 X 4.25 X 6.385 is this the combo that they use to get to 540cu in

Cam is .632 and .632 lift on 114 center, pistons are SRP dome top +10cc. Have dyno sheets but need to find them, actually went to the shop and witnessed a few dyno runs. Yes 540ci with rods 6.385, bore is 4.500 and stroke is 4.250.

After reading countless articles and contributions from various forums, my goal is to be slightly over 500hp. I know I do not have the pocket depth to build a 90+ mph boat so I decided to stay mostly stock. I plan on keeping the heads and rotating assembly stock. I want to add a cam and cmi's The opinions on cams is all over the place. So the last 2 pieces of the puzzle are cam and someone who can program my ECU to match the upgraded exhaust and cam. Any Ideas? I appreciate everyone's input it is appreciated .

Crane 168741.Or if you want to tone it down a bit a crane 731.I have 2 of them out of 500 EFI's if your interested $250 our money about $200 in yours plus shipping.
Quite a few in your part of the world to do your ECU.Google.